The International’s prize pool is funded by sales of the Compendium, an interactive tournament guide that offers many features and perks to the event’s spectators. Valve has set stretch goals for reaching prize pool milestones, similar to a Kickstarter, and each $10 sale of the Compendium adds $2.50 to the The International prize pool.

Hitting $6 million unlocked what was thought to be the final goal, a base customization item for Compendium owners. Now, a whole new set of rewards promises to push the prize purse ever higher.

The rewards range from major game systems to cosmetic perks and even a concert with Dota’s most popular electronic artist.

At $7.2 million, for example, Compendium owners will get to vote on a champion to receive an alternate voice. All Dota players will receive new, upgraded creep models after their team knocks off an enemy barracks at $9.2 million. $400,00 on top of that will add a new quest system to the game.

The $8.8 million milestone unlocks the most Dota thing ever—a live broadcast of the The International afterparty featuring Finnish trance DJ Darude, of Sandstorm fame.

And the final reward allows you to taunt your opponents with victory chant at the beginning of each match, then records how many times you make good on the promises.

The tournament is set for July 18-21 in Seattle, so there’s still two months for fans to throw their money Valve’s way. Considering how fast the pool has grown since the Compendium’s release twelve days ago—$4.4 million over the $1.6 million contributed by Valve—the $10 million stretch goal seems quite realistic. At the rate of growth sustained so far, it’ll be just eleven days before Valve announces new rewards for a $20 million purse.

The International already holds the record for prize money at an esports event, and the $6 million pool already ranks it ahead of some of the world’s richest sporting competitions. The $10 million mark would push Dota past golf’s prestigious The Masters and its $9 million in prizes.

Largely unmentioned in all the hype surrounding the prize purses is Valve’s own take. With only 25 percent of every $10 Compendium sale going to the prize pool, Valve is raking in the cash, making the development costs associated with each stretch reward seem cheap by comparison.

With $4.4 million added to the prize pool so far, Compendium sales total around $17.6 million. That’s $13.2 million headed Valve’s way, before subtracting their $1.6 million prize pool contribution. To push the prize pool to the $10 million stretch goal, it’ll take $33.6 million in Compendium sales. That’s a large wad of cash for Valve, $25.2 million. Not bad for a free-to-play game.

Of course, that’s still a far cry from the $957 million free-to-play shooter CrossFire, a Counter-Strike clone popular in Asia, pulled in last year, or the $624 million earned by League of Legends. Last year, Valve’s own Team Fortress 2 topped Dota’s revenue with $139 million. But that’s most likely going to change in 2014.

And maybe sooner than we think. When someone—Na’Vi? Alliance?—take home whatever gargantuan prize awaits them, we’ll all know who the real winners are: Valve, and Dota’s esports fans.